1. Field of the Invention
The present invention relates to a bearing mechanism, a spindle motor having the bearing mechanism, and a data storage medium drive having the spindle motor.
2. Description of the Related Art
In recent years, an oil bearing or a fluid dynamic pressure bearing is frequently used in a data storage medium drive such as a hard disk drive. Since such bearing mechanisms use lubricant (e.g., lubricating oil) at more than two locations therein, it is critical that the lubricant is retained securely within the bearing mechanism.
In order to securely retain the lubricant within the bearing mechanism, elements included in the bearing mechanism are pressed, fitted, and connected via an adhesive. Also, welding may be used to connect the elements in such a bearing mechanism.
To be more specific, an approximately cylindrical metallic case which accommodates therein a sleeve which supports a rotational axis and a bearing mechanism having a cover to close an opening of the metallic case may be laser welded at the opening of the metallic case and the cover.
Generally, when laser welding is carried out, metallic vapor (hereinafter, fumes) is generated when a weldment is heated to a high temperature and adhered to a welded portion or the like. The fumes include oxidized particles of the weldment, which, when adhered to the welded portion or the like, may fall therefrom due to vibrations or the like. When such particles from the fumes contaminate the lubricant, the bearing mechanism may be damaged. Also, elements having the particles thereon may appear very dark which requires an additional process of removing the particles. Also, the elements having the particles thereon may have reduced anti-corrosion characteristics.
Also, due to thermal strain of the laser welding, the welded portion may be damaged (i.e., cracked) from which the lubricant may leak causing the bearing mechanism to malfunction.